1. Field of the Invention
This invention relates to a novel synthetic porous crystalline material, MCM-67, to a method for its preparation and to its use in catalytic conversion of organic compounds.
2. Description of the Prior Art
Zeolitic materials, both natural and synthetic, have been demonstrated in the past to have catalytic properties for various types of hydrocarbon conversion. Certain zeolitic materials are ordered, porous crystalline aluminosilicates having a definite crystalline structure as determined by X-ray diffraction, within which there are a large number of smaller cavities which may be interconnected by a number of still smaller channels or pores. These cavities and pores are uniform in size within a specific zeolitic material. Since the dimensions of these pores are such as to accept for adsorption molecules of certain dimensions while rejecting those of larger dimensions, these materials have come to be known as xe2x80x9cmolecular sievesxe2x80x9d and are utilized in a variety of ways to take advantage of these properties.
Such molecular sieves, both natural and synthetic, include a wide variety of positive ion-containing crystalline silicates. These silicates can be described as a rigid three-dimensional framework of SiO4 and Periodic Table Group IIIA element oxide, e.g., AlO4, in which the tetrahedra are cross-linked by the sharing of oxygen atoms whereby the ratio of the total Group IIIA element, e.g., aluminum, and silicon atoms to oxygen atoms is 1:2. The electrovalence of the tetrahedra containing the Group IIIA element, e.g., aluminum, is balanced by the inclusion in the crystal of a cation, for example an alkali metal or an alkaline earth metal cation. This can be expressed wherein the ratio of the Group IIIA element, e.g., aluminum, to the number of various cations, such as Ca/2, Sr/2, Na, K or Li, is equal to unity. One type of cation may be exchanged either entirely or partially with another type of cation utilizing ion exchange techniques in a conventional manner. By means of such cation exchange, it has been possible to vary the properties of a given silicate by suitable selection of the cation. The spaces between the tetrahedra are occupied by molecules of water prior to dehydration.
Prior art techniques have resulted in the formation of a great variety of synthetic zeolites. Many of these zeolites have come to be designated by letter or other convenient symbols, as illustrated by zeolite A (U.S. Pat. No. 2,882,243); zeolite X (U.S. Pat. No. 2,882,244); zeolite Y (U.S. Pat. No. 3,130,007); zeolite ZK-5 (U.S. Pat. No. 3,247,195); zeolite ZK-4 (U.S. Pat. No. 3,314,752); zeolite ZSM-5 (U.S. Pat. No. 3,702,886); zeolite ZSM-11 (U.S. Pat. No. 3,709,979); zeolite ZSM-12 (U.S. Pat. No. 3,832,449), zeolite ZSM-20 (U.S. Pat. No. 3,972,983); ZSM-35 (U.S. Pat. No. 4,016,245); zeolite ZSM-23 (U.S. Pat. No. 4,076,842); zeolite MCM-22 (U.S. Pat. No. 4,954,325); and zeolite MCM-35 (U.S. Pat. No. 4,981,663), merely to name a few.
The SiO2/Al2O3 ratio of a given zeolite is often variable. For example, zeolite X can be synthesized with SiO2/Al2O3 ratios of from 2 to 3; zeolite Y, from 3 to about 6. In some zeolites, the upper limit of the SiO2/Al2O3 ratio is unbounded. ZSM-5 is one such example wherein the SiO2/Al2O3 ratio is at least 5 and up to the limits of present analytical measurement techniques. U.S. Pat. No. 3,941,871 (Re. 29,948) discloses a porous crystalline silicate made from a reaction mixture containing no deliberately added alumina in the starting mixture and exhibiting the X-ray diffraction pattern characteristic of ZSM-5. U.S. Pat. Nos. 4,061,724, 4,073,865 and 4,104,294 describe crystalline silicates of varying alumina and metal content.
One known zeolite is VPI-8 which is described by M. A. Camblor, M. Yoshikawa, S. I. Zones, M. E. Davis xe2x80x9cSynthesis of VPI-8: The first Large Pore Zincosilicate,xe2x80x9d in Synthesis of Porous Materials: Zeolites, Clays and Nanostructures, edited M. L. Occelli and H. Kessler, Marcel Dekker Inc., New York, 1996, p 243-261; and by M. Yoshikawa, S. I. Zones, M. E. Davis xe2x80x9cSynthesis of VPI-8 I. The effects of Reaction Componentsxe2x80x9d, in Microporous Materials, 1997, 11, 127-136. VPI-8 is isostructural with SSZ-41 which is described in U.S. Pat. No. 5,591,421. Both VPI-8 and SSZ-41 necessarily require the presence of zinc.
MCM-67 of the present invention appears to be closely related in structure to VPI-8 and SSZ-41 but is synthesized in the absence of zinc. MCM-67 is synthesized in the presence of manganese and/or cobalt ions and can be synthesized as a boro-metallosilicate or as a copper silicate.
The present invention is directed to a novel porous crystalline material, named MCM-67, which in its calcined form is characterized by an X-ray diffraction pattern including values substantially as set forth in Table I of the specification and has a composition comprising the molar relationship
YO2:(n)X2O3:(p)ZO
wherein X is a trivalent element, Y is a tetravalent element and Z is cobalt and/or manganese, n is from 0 to 0.5, and p is from 0.0001 to 0.5 and wherein the porous crystalline material does not contain zinc.
The invention further resides in a method for the preparation of MCM-67, and the conversion of organic compounds contacted with an active form thereof